Fractation of oil obtained by pyrolysis of lignocellulosic materials to recover a phenolic fraction for use in making phenol-formaldehyde resins

ABSTRACT

A method is provided for fractionation of oil obtained by pyrolysis of lignocellulosic materials to obtain useful chemical fractions, including a phenolic fraction which is suitable as a total or partial replacement for phenol in making phenol-formaldehyde resins. The method comprises mixing the oil with a strong base such as sodium hydroxide to a pH level at which the neutral fraction of the oil is selectively soluble in a solvent such as methylene chloride or ether, and the mixture is extracted with the solvent to obtain a first extract containing the solvent and the neutral fraction, and a first raffinate containing the remaining fractions of the oil, i.e., the phenolic fraction, the organic acids fraction and an amorphous residue. The neutral fraction is recovered by distillation and the first raffinate is mixed with sulfuric acid to lower its pH to a level at which the phenolic fraction is selectively soluble in the solvent. This raffinate is extracted with the solvent to obtain a second extract containing the solvent and the phenolic fraction and a second raffinate containing the organic acids and the residues. The phenolic fraction is recovered by distillation and the second raffinate is mixed with sulfuric acid to lower its pH to a level at which the organic acids are selectively soluble in the solvent. After separation of the residues, the second raffinate is extracted with the solvent to obtain a third extract which is distilled to recover the organic acids fraction of the oil. The phenolic fraction may be used as partial or total replacement for pure phenol in making phenol-formaldehyde resins.

This is a divisional application of application Ser. No. 918,040 filedJune 22, 1978.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a method of fractionation of oilobtained by pyrolysis of lignocellulosic materials, and is particularlyrelated to the fractionation of such oil to recover valuable fractions,including a phenolic fraction. This invention is also concerned with theuse of the phenolic fraction obtained from this fractionation to makephenol-formaldehyde resins.

2. The Prior Art

Lignocellulosic wastes such as bark, sawdust, treetops, limbs and thelike are pyrolyzed on a commercial scale to obtain a low BTU fuel gas,char for use in making charcoal briquets or activated carbon, and apyrolytic oil fraction comprising a complex mixture of various chemicalcompounds presently used as a low cost fuel. Fractionation of thepyrolytic oil yields valuable chemical products, including a phenolicfraction. It has been found that this phenolic fraction can be used aspartial or total replacement for pure phenol in makingphenol-formaldehyde resins.

Accordingly, it is an object of this invention to provide a method ofproducing various useful chemicals to replace chemicals currentlyderived from petroleum.

It is a further object of this invention to derive various usefulchemicals from chemical separation of the oily fraction obtained by thepyrolysis of lignocellulosic wastes such as bark, sawdust, treetops,limbs and the like.

It is still another object of this invention to obtain a fraction richin phenols and polyphenols by chemical fractionation of such pyrolyticoils.

It is also an object of this invention to use the phenolic fractionobtained from fractionation of such pyrolytic oils in makingphenol-formaldehyde resins.

The foregoing and other objects of this invention will be more clearlycomprehended from the ensuing detailed description of the inventiontaken in conjunction with the accompanying drawing which is a simplifiedschematic flow representation of the fractionation method of thisinvention.

SUMMARY OF INVENTION

In accordance with this invention the oil derived from pyrolysis oflignocellulosic waste materials is first mixed with a strong basicsolution such as a sodium hydroxide solution. The resulting blackcolored mixture with a pH range of from about 11 to about 13 is thencontacted with an appropriate solvent such as methylene chloride in asuitable extraction unit. A first extract is recovered from this unitcomprising the neutral fraction of the oil which is subjected todistillative operation to remove the solvent and recover the neutralfraction.

The raffinate from this unit is mixed with a mineral acid, such assulfuric acid, or with carbon dioxide to lower its pH to the range offrom about 7.5 to about 9.0, before it is introduced into a secondextraction unit wherein it is contacted with a solvent such as methylenechloride. By this extraction step the phenolic fraction is removed withthe solvent as the second extract which is distilled to recover thesolvent and the phenolic product. The second raffinate from the secondextraction unit is mixed with a mineral acid such as sulfuric acid toreduce its pH to the range of from about 1.0 to about 4.0, the tarryresidues separated and the mixture is then introduced into a thirdextraction unit wherein it is contacted with methylene chloride. Thethird extract from this unit, after the removal of the tarry product isdistilled to separate the solvent and recover the organic acidsfraction. The third raffinate from the third extraction unit isneutralized and transported to a waste disposal system.

The phenolic fraction obtained by this fractionation method is used astotal or partial replacement for petroleum-derived phenol in makingphenol-formaldehyde resins. The reaction of formaldehyde with thisphenolic fraction is carried out in the presence of a base catalyst,preferably under reflux conditions, until the viscosity of the resultingphenol-formaldehyde polymer reaches about 500 to about 1000 cps.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with this invention the oily fraction obtained bypyrolysis of lignocellulosic waste materials is upgraded by a uniquechemical separation or fractionation method to produce four fractions; aneutral fraction, a phenolic fraction, an amorphous residue and afraction consisting of organic acids. These fractions are obtained by aseries of selective extractions or fractionations under carefullycontrolled conditions and a judicious choice of the extraction solvent.

Thus, according to the method of this invention, and referring to thedrawing, the oily fraction obtained from the pyrolysis oflignocellulosic wastes is introduced via conduit 101 into a mixingvessel 103 wherein it is thoroughly mixed with a strong basic solution,such as a dilute solution of sodium hydroxide, which is introduced intothe mixer 103 via conduit 105, thereby converting the acidic componentsof the oil (carboxylic acids and phenols) to their respective salts. Theterm "lignocellulosic waste" employed herein is intended to includebark, sawdust, treetops, limbs, and the like, or mixtures thereof.Moreover, while sodium hydroxide is the alkali of choice, other basessuch as potassium hydroxide and ammonium hydroxide may be employedefficaciously and in varying concentrations.

The amount of sodium hydroxide used to convert the acidic components ofthe oil into their respective salts must be sufficient to result in amixture having a pH of from about 11 to about 13. At his pH range, theneutral components of the oil are selectively soluble in the solventsemployed in the practice of this invention.

The oil-base mixture from mixer 103 is then introduced via conduit 107into a fractionation or extraction column 109 wherein it is contactedwith a solvent introduced into the column 109 via conduit 111 emanatingfrom a solvent storage tank 113. The solvents which are particularlyeffective for the removal of the neutral fractions of the oil in thepractice of this invention are methylene chloride, ether, chloroform,butanol and hydrocarbon solvents.

The relative volumetric flow rates of the solvent to the oil-basemixture may vary from about 3:1 to about 1:1. The temperature at whichthe extraction of the neutral fraction of the oil is carried outdepends, to a great extent, on the boiling point of the solvent. Ingeneral, and for the solvents employed herein, this extraction step maybe conveniently carried out at ambient temperatures.

The extract from column 109 is withdrawn via conduit 115 and introducedinto a distillation column 117 wherein the solvent is recovered by steamdistillation, or any other suitable method, and removed from the column117 via conduit 119. It may be cooled and condensed and returned to thesolvent storage tank 113, if desired. The extract which is withdrawnfrom distillation column 117 via conduit 121 consists of the neutralfraction of the oil. This fraction may be stored in a storage vessel(not shown) for further use.

The raffinate from the extraction column 109 is withdrawn via conduit123 and introduced into a mixing vessel 125 wherein it is mixed with a50% sulfuric acid solution introduced into the mixing vessel 125 viaconduit 127 withdrawn from an acid storage tank 129. The raffinate fromcolumn 109 is mixed with sufficient amount of sulfuric acid in the mixer125 until the pH of the resulting mixture is within the range of fromabout 7.5 to 9.0. It has been found that at this pH range, the phenolicfraction of the oil is selectively soluble in the solvents employed inthe practice of this invention. Thus, the raffinate from column 109,after thorough mixing and pH adjustment in mixer 125, is withdrawn fromthe mixer 125 via conduit 129 and introduced into a second extraction orfractionation column 131 wherein it is contacted with the solventintroduced into the column 131 via conduit 133 from the solvent storagetank 113.

The relative volumetric flow rates of the solvent and the feed in column131 may vary from about 3:1 to about 1:1. Once again, the extractiontemperature in column 131 depends on the boiling point of the solventbut, in general, ambient temperatures are quite satisfactory.

The extract from column 131 is withdrawn via conduit 135 and distilledin the presence of steam in distillation column 137 to recover thephenolic fraction via conduit 139. The solvent is removed overhead viaconduit 141, cooled and condensed, and may be returned to the solventstorage tank 113, if desired.

The raffinate from the fractionation column 131 is withdrawn via conduit143, introduced into a mixing vessel 145 wherein it is mixed withsufficient quantity of a 50% sulfuric acid solution withdrawn from theacid tank 129, and introduced into the mixer 145 via conduit 127', untilthe pH of the resulting mixture is in the range of from about 1.0 toabout 4.0. After separating a tarry residue via conduit 147, the mixturefrom mixer 145 is withdrawn via conduit 149 and fed to a thirdfractionation or extraction column 151 wherein the mixture is contactedwith the solvent withdrawn from solvent storage tank 113 and introducedinto the column 151 via conduit 153.

Once again the relative volumetric flow rates of the solvent and thefeed in column 151 may vary from about 3:1 to about 1:1. The optimumtemperature for the extraction of the organic acids fraction of the oilin column 151 depends on the boiling point of the solvent, and again,ambient temperatures have been found to be quite satisfactory.

The extract from column 151 is withdrawn via conduit 155 and introducedinto a separation tank 157 wherein tarry products are separated andwithdrawn via conduit 159 and the tar-free mixture introduced viaconduit 161 to a distillation column 163 wherein the mixture is steamdistilled to remove the solvent overhead via conduit 165, cooled andcondensed, and returned to the solvent storage tank, if desired. Theextract from the distillation column 163, which is withdrawn via conduit167, consists basically of the organic acids fraction of the oil.

The raffinate from column 151 which is withdrawn via conduit 169 may beconveyed to a neutralization and disposal tank (not shown).

The following examples will serve to further illustrate thefractionation method of this invention. Methylene chloride was thesolvent employed in one example and ether was the solvent employed inthe other example. The same standard laboratory equipment were used inboth examples, except that the extraction column in the example usingmethylene chloride was different from the extraction column in theexample using ether. It must be understood, however, that these examplesare merely intended to further illustrate the practice of this inventionwithout in any way limiting its scope.

EXAMPLE I

One hundred milliliters (99.28 grams dry weight) of distillate oil and300 ml. of 10% sodium hydroxide (30 grams NaOH) were mixed thoroughly toobtain a black mixture having a pH of 11. The distillate oil employed inthis example was derived from the pyrolysis of sawdust and had a densityof 1.082 gm/cc, a pH of 2.60 and contained 14.3% water. The blackmixture was charged to a 1 liter continuous liquid-liquid extractioncolumn equipped with an overhead condenser and a flask, and the mixturewas extracted with methylene chloride at 70° F. until a clear solutionwas obtained. The contents of the extraction column were thentransferred to a 2 liter separatory funnel wherein it was allowed toseparate into an organic bottom layer and a top aqueous layer. Theorganic bottom layer was transferred to the extract in the boiling flaskand dried with anhydrous sodium sulfate, and the solvent was thenstripped off on a rotary evaporator to obtain 32.8 grams of a darkbrown, viscous oil constituting the neutral fraction.

The alkaline aqueous phase which had a pH of 10.2 was mixed with dry iceto lower its pH to 7.8 and, 500 ml. of water was added thereto and themixture transferred to a 2 liter extractor and contacted with methylenechloride at 70° F. and then transferred to a 2 liter separatory funnel.The bottom solvent layer from the separatory funnel was combined withthe extract from the boiling flask and dried with anhydrous sodiumsulfate, and the solvent was stripped off on a rotary evaporator toobtain 21.77 grams of a black, highly viscous product constituting thephenolic fraction of the wood waste distillate oil.

The alkaline aqueous phase was treated with 75 ml. of a 50% sulfuricacid solution to reduce its pH from 9 to 2 resulting in some tarseparation. The acidic phase was transferred to a 2 liter liquid-liquidextractor wherein it was contacted with methylene chloride at 70° F.,and the contents of the extractor were transferred to a 2 literseparatory funnel. The bottom solvent layer from the separatory funnelwas combined with the extract in the boiling flask and dried withanhydrous sodium sulfate, and the solvent was stripped off on a rotaryevaporator to obtain 9.41 grams of an amber color oil representing theorganic acid fraction of the oil.

The black tar recovered in the previous step was subjected to azeotropicdistillation with toluene and the black solid product formed in thisdistillation was separated from toluene and dried to obtain 16.5 gramsof a dark brown, amorphous product.

The toluene solution was stripped off on a rotary evaporator and yielded2.30 grams of a brown semi-solid material which constituted anadditional quantity of organic acids. In an alternative procedure, theblack tar is digested in hot water, separated by filtration and dried togive a dark brown amorphous solid.

Table I below summarizes the yields of the various fractions obtained inthis Example.

                  TABLE I                                                         ______________________________________                                                                       Dry                                                         Weight   Water    Weight Yield                                   Fraction     gm       %        gm     %                                       ______________________________________                                        Distillate Oil                                                                             115.84   14.3     99.28  --                                      Neutrals     33.05    0.76     32.80  33.04                                   Phenols      21.92    0.67     21.77  21.93                                   Acids        9.56     1.53     9.41   9.48                                    Residues     16.74    2.32     18.65  18.79                                   Total Recovery                        83.24                                   ______________________________________                                    

EXAMPLE II

One hundred and fifty milliliters of distillate oil (117.26 grams on dryweight basis) was thoroughly mixed with 300 ml. of 25% sodium hydroxidesolution (75 grams NaOH) to obtain a black mixture having a pH of 11.96.The source of the distillate oil was the same as that used in Example I.The black mixture was then transferred to a 1 liter continuousliquid-liquid extractor and contacted therein with ether at 70° F. untila clear solution was obtained. The contents of the extractor weretransferred to a separatory funnel and allowed to separate, and thebottom aqueous layer was drained into a beaker and set aside. The toporganic phase was combined with the extract from the boiling flask anddried over anhydrous sodium sulfate, and the solvent was stripped off ona rotary evaporator to yield 37.79 grams of dark brown oil whichconstitutes the neutral fraction of the wood wastes distillate oil. Uponstanding, crystalline solids separated out from this fraction.

The aqueous layer which was set aside was mixed with a 50% sulfuric acidsolution until its pH was reduced from 13.75 to 7.90, and the resultingblack mixture was transferred to the extractor and contacted with etherat 70° F. After completion of the extraction, the contents of theextractor were transferred to a separatory funnel wherein two layerswere formed; a bottom aqueous layer which was drained into a beaker andset aside, and a top organic layer which was combined with the extractin the boiling flask, dried with anhydrous sodium solfate and thesolvent stripped off on a rotary evaporator. 38.72 grams of a thickblack oil was obtained representing the phenolic fraction of thedistillate oil.

The aqueous phase was mixed with 150 ml. of a 50% sulfuric acid solutionto lower its pH to 2 and the mixture was transferred to the extractorwherein it was contacted with ether at 70° F. The contents of theextractor were then transferred to a separatory funnel wherein a blacktar separated out which was removed and set aside. The bottom aqueousphase from the funnel was discarded and the top organic layer wascombined with the extract from the boiling flask, dried with sodiumsulfate, and the solvent stripped off on a rotary evaporator to yield28.19 grams of a brown oil which represents the organic acid fraction ofthe wood waste distillate oil.

The tar obtained in the previous step was dehydrated by azeotropicdistillation with toluene to yield 4.76 grams of a dark brown solid. Inan alternative procedure, the black tar is digested in hot water,separated by filtration and dried to give a dark brown amorphous solid.

The yields of various fractions obtained in this example are shown inTable II below.

                  TABLE II                                                        ______________________________________                                                                        Dry                                                     Weight       Water    Weight Yield                                  Fraction  gm           %        gms    %                                      ______________________________________                                        Distillate Oil                                                                          136.82       14.3     117.26 --                                     Neutrals  40.60        6.92     37.79  32.23                                  Phenols   20.66        4.76     38.72  33.02                                  Acids     36.72        23.23    28.19  24.04                                  Residues  4.95         3.93     4.76    4.06                                            Total Recovery               93.35                                  ______________________________________                                    

From the foregoing description it is evident that this inventionprovides a unique method of upgrading distillate oil to provide variouschemical fractions, including a phenolic fraction.

A combination of gas chromatographic and infrared spectroscopiccharacterization of the phenolic fraction obtained by the method of thisinvention revealed the presence of phenol, o-cresol, p-cresol, guaicol,4-methyl guaicol, 4-ethyl guaicol, isoeugenol, eugenol, a benzophenonederivative and delignol.

The organic acids fraction obtained by the fractionation method of thisinvention includes acetic acid, propionic acid, butyric acid and otherhigher acids.

The fractionation of distillate oil in accordance with this inventionmay be carried out continuously, semi-continuously or in a batchwisemanner using readily available equipment and reagents. The solventextraction step may be carried out concurrently or countercurrently,although countercurrent, liquid-liquid extraction constitutes thepreferred practice, since it is more efficient and is readily adaptableto large scale industrial operation.

While in the foregoing description the invention has been described indetail, and with certain degrees of particularity, it is evident tothose skilled in the art that several changes and modifications may bemade which are suggested from the detailed disclosure herein, and whichare nevertheless contemplated by, and obvious from the description ofthis invention. For example, and in a different embodiment of theinvention, the oil may be first dissolved in the solvent and theresulting solution treated with 10% sodium hydroxide solution until thepH of the mixture is from about 11 to about 13. This treatment resultsin an organic phase containing the neutral fraction of the oil and anaqueous phase containing the remaining fractions. The organic phase maybe distilled to recover the neutral fractions, and the aqueous phase istreated with sulfuric acid or gaseous carbon dioxide to reduce its pH tothe range of from about 8 to about 8.5, and thereafter subjected to aseries of extractive and distillative operations, essentially asdescribed in connection with the previous embodiment, in order torecover the phenolic fraction and the acids fraction of the oil.

Example III below illustrates this embodiment of the invention.

EXAMPLE III

Five hundred and two grams of filtered distillate oil obtained frompyrolysis of a mixture of bark and saw dust was dissolved in 1250 ml. ofmethylene chloride and the resulting solution was separated from theinsolubles. The insolubles were then extracted with several portions ofmethylene chloride to give 106 grams of insoluble oil. The resultingsolution and the extract were combined and treated 3 times with 460 ml.of 10% sodium hydroxide in an ice bath and the organic phase was driedand evaporated to give 129 grams of neutral fraction, corresponding to ayield of 31%.

The combined aqueous phase with a pH of 12.3 was treated with gaseouscarbon dioxide to lower its pH to 8. This aqueous phase was extractedseveral times with methylene chloride, and the organic phase was driedand evaporated to give 139 gm. of phenolic fraction, corresponding to ayield of 33%. The aqueous phase was acidified with 280 ml. of 10%sulfuric acid to a pH of 2 and extracted several times with methylenechloride, and the resulting solids were filtered off to give 7 gm. oforganic acids. The combined organic layers were then dried andevaporated to give an additional 12 grams of organic acids,corresponding to a combined yield of 5%.

As it was previously mentioned, the phenolic fraction obtained by thefractionation of lignocellulosic waste materials as hereinbeforedescribed can be employed as partial or total replacement forpetroleum-derived phenol in the synthesis of phenol-formaldehyde resins.Since these phenolic fractions contain substantial amounts ofpolyphenolic compounds, the resulting phenol-formaldehyde resins arehighly cross-linked polymers.

Thus, phenol-formaldehyde resins may be made by reacting formaldehydewith the phenolic fraction in the presence of a base catalyst such assodium hydroxide, preferably under reflux conditions, until theviscosity of the resulting phenol-formaldehyde polymer is in the rangeof from about 500 cps to about 1000 cps. While such phenolic fractionsmay be used as total replacement for petroleum-derived phenol, it isgenerally recommended that the phenolic reactant contains from about 25to about 75 weight percent phenolic fraction obtained from fractionationof such distillate oils, with the remainder being petroleum-derivedphenol.

EXAMPLE IV

Twenty five grams of a phenolic fraction obtained from the fractionationof distillate oil obtained by pyrolysis of a mixture of sawdust and barkwas mixed with 25 grams of petroleum-derived phenol, 87 grams of 37%formaldehyde solution, 13 grams of 50% sodium hydroxide solution and 60ml. of water. The mixture was then transferred to a 500 ml. reactionflask equipped with a stirrer, reflux condenser and a thermometer andreacted under reflux conditions for 25 minutes. Thereafter an additional15 grams of a 50% sodium hydroxide solution was added to the content ofthe reaction flask and the resulting mixture was refluxed for another 25minutes. After this period, an additional 15 grams of a 50% sodiumhydroxide solution was added to the reaction flask and the mixture wasrefluxed for another 30 minutes. The viscosity of the resulting resin atthis state was determined by a Wells-Brookfield Micro Viscometer to be208 cps. The reaction mixture was further refluxed for an additional 25minutes to obtain 209 grams of finished resin representing a yield of 87weight percent. The viscosity of the finished resin was determined to be662 cps.

The phenol-formaldehyde resins made by the reaction described herein maybe used to make adhesive preparations which may be used for laminationplywood. Thus, 60 grams of the phenol-formaldehyde resin made as inExample IV was mixed in a beaker with 12 grams of Furafil (made byQuaker Oats Co.), 6 grams of 50% solution of sodium hydroxide and 22grams of water to make an adhesive having a viscosity of 343 cps. Theresulting adhesive was used to laminate veneer panels which were testedfor wood failure. The results obtained by using adhesives made fromphenol-formaldehyde resins made as in Example IV were comparable to theresults obtained with adhesives made from phenol-formaldehyde resinsusing petroleum derived phenols.

What is claimed is:
 1. A method of recovering a phenolic fraction fromdistillate oil obtained by pyrolysis of lignocellulosic waste materials,and making phenol-formaldehyde resins therefrom which comprises:(a)mixing said oil with a base selected from the group consisting of sodiumhydroxide, potassium hydroxide and ammonium hydroxide to obtain amixture having a pH in the range of from about 11 to about 13; (b)contacting said mixture, in a first extraction zone, with a solventselected from the group consisting of ether, methylene chloride,chloroform, butanol and hydrocarbons, wherein the volumetric flow ratesof the solvent to said mixture is from about 3:1 to about 1:1 to therebyselectively extract the neutral fraction of said oil; (c) removing afirst extract and a first raffinate from said first extraction zone andrecovering the neutral fraction from said first extract; (d) mixing saidfirst raffinate with a mineral acid or carbon dioxide until the pH ofsaid raffinate is lowered to the range of from about 7.5 to about 9.0and contacting the resulting mixture with said solvent in a secondextraction zone, wherein the volumetric flow rates of the solvent tosaid mixture is from about 3:1 to about 1:1, to thereby selectivelyextract the phenolic fraction of said oil; (e) removing a second extractcontaining said phenolic fraction, and a second raffinate from saidsecond extraction zone, (f) recovering said phenolic fraction from saidsecond extract, and (g) reacting said phenolic fraction withformaldehyde in the presence of a metal hydroxide catalyst until theviscosity of the resulting phenol-formaldehyde resin reaches from about500 cps to about 1000 cps.
 2. A method as in claim 1 wherein saidreaction is carried out under reflux conditions.
 3. A method as in claim1 wherein said catalyst is sodium hydroxide.
 4. A method as in claim 2wherein said catalyst is sodium hydroxide.
 5. A method of makingphenol-formaldehyde resin which comprises reacting formaldehyde with thephenolic fraction recovered from fractionation of distillate oilobtained by pyrolysis of lignocellulosic waste materials, said reactionbeing carried out in the presence of a metal hydroxide catalyst untilthe viscosity of the resulting phenol-formaldehyde resin reaches fromabout 500 cps to about 1000 cps.
 6. A method as in claim 5 wherein saidreaction is carried out under reflux conditions.
 7. A method as in claim5 wherein said catalyst is sodium hydroxide.
 8. A method as in claim 6wherein said catalyst is sodium hydroxide.
 9. A method of recovering aphenolic fraction from distillate oil obtained by pyrolysis oflignocellulosic waste materials and making phenol-formaldehyde resinstherefrom which comprises:(a) dissolving said oil in a solvent selectedfrom the group consisting of ether, methylene chloride, chloroform,butanol and hydrocarbons; (b) treating the resulting solution with abase selected from the group consisting of sodium hydroxide, potassiumhydroxide and ammonium hydroxide, wherein the amount of said base iscalculated to produce a mixture having a pH of from about 11 to about 13to thereby obtain an organic phase containing the neutral fraction ofsaid oil and an aqueous phase containing the phenolic fraction and acidsfraction of said oil; (c) separating said aqueous phase and mixing itwith a mineral acid or gaseous carbon dioxide until its pH is lowered tothe range of from about 7.5 to about 9.0 and contacting the resultingmixture with said solvent in an extraction zone to selectively extractthe phenolic fraction of said oil; (d) removing an extract containingsaid phenolic fraction and recovering said phenolic fraction from saidextract; and (e) reacting said phenolic fraction with formaldehyde inthe presence of a metal hydroxide catalyst until the viscosity of theresulting phenol-formaldehyde resin reaches from about 500 cps to about1000 cps.
 10. A method as in claim 9 wherein said phenolic fraction isrecovered by distillation.
 11. A method as in claim 9 wherein saidreaction is carried out under reflux conditions.
 12. A method as inclaim 9 wherein said catalyst is sodium hydroxide.
 13. A method as inclaim 11 wherein said catalyst is sodium hydroxide.